Torque transmitting shaft

ABSTRACT

A torque transmitting shaft includes a first member and a second member. The first member extends along an axis and has an inner surface extending between a first end and a second end. The inner surface defines a plurality of first engagement elements disposed proximate the first end. The second member extends along the second axis and has a first end portion and an intermediate portion extending from the first end portion. An end of the intermediate portion is fixedly attached to the second end. The first end portion has a first spline portion and each member of the first spline portion is received within corresponding engagement elements of the plurality of first engagement elements.

CROSS-REFERENCES TO RELATED APPLICATIONS

This patent application claims priority to U.S. Provisional PatentApplication Ser. No. 62/075,498, filed Nov. 5, 2014, which isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

The present invention relates to a torque transmitting shaft havingmultiple torsional stiffness rates.

Vehicle drive lines transmit torque or power from a drive source, suchas an internal combustion engine, to vehicle wheels. The torque or powermay be transmitted through a series of driveline components such asgears, joints, and shafts. The driveline components provide a level oftorsional stiffness to satisfy performance requirements. The drivelinecomponents also provide a level of compliance to reduce unwanted noise,vibration, or harshness. Some vehicle drive lines include driveshaftsthat are a simple one-piece torque transmitting shaft having a singletorsional stiffness rate.

SUMMARY OF THE INVENTION

In one embodiment of the present invention, a torque transmitting shaftis provided. The torque transmitting shaft includes a first member and asecond member. The first member extends along an axis and has an innersurface extending between a first end and a second end. The innersurface defines a plurality of first engagement elements disposedproximate the first end. The second member extends along the axis and isreceived within the first member. The second member includes a first endportion, a second end portion, and an intermediate portion extendingbetween the first end portion and a second end portion. The first endportion has a first spline portion and each member of the first splineportion is received within the corresponding engagement elements of theplurality of first engagement elements. A first torsional stiffness rateis provided by the second member while a first torque is applied to thesecond member and while there is a tangential clearance between a memberof the first spline portion and an engagement element of the pluralityof first engagement elements. A second torsional stiffness rate isprovided by at least one of the first member and the second member whilea second torque is applied to the second member and while there is notangential clearance between the member of the first spline portion andthe engagement element of the plurality of the first engagementelements.

In another embodiment of the present invention, a torque transmittingshaft is provided. The torque transmitting shaft includes a first memberextending along an axis, a second member extending along the axis andreceived within the first member, and a first pin. The first member hasa generally cylindrical body extending between a first end and a secondend. The first end has a first opening extending substantiallyperpendicular to the axis and the second end has a second openingextending substantially perpendicular to the axis and spaced apart fromthe first opening. The second member has a first end portion, a secondend portion, and an intermediate portion extending between the first endportion and the second end portion. The first end portion has a firstend portion opening extending substantially perpendicular to the axisand the second end portion has a second end portion opening extendingsubstantially perpendicular to the axis. The first pin is receivedwithin the first opening and the first end portioning opening. A firsttorsional stiffness rate is provided by the second member while thefirst torque is applied to the second member and while there is atangential clearance between an exterior surface of the first pin and anedge of the first opening. A second torsional stiffness rate is providedby at least one of the first member and the second member while a secondtorque is applied to the second member and while there is no tangentialclearance between the exterior surface of the first pin and the edge ofthe first opening.

In yet another embodiment of the present invention, a torquetransmitting shaft is provided. The torque transmitting shaft includes afirst member and a second member. The first member extends along an axisand has an inner surface extending between a first end and a second end.The inner surface defines a plurality of first engagement elementsdisposed proximate the first end. The second member extends along thesecond axis and has a first end portion and an intermediate portionextending from the first end portion. An end of the intermediate portionis fixedly attached to the second end. The first end portion has a firstspline portion and each member of the first spline portion is receivedwithin corresponding engagement elements of the plurality of firstengagement elements.

These and other advantages and features will become more apparent fromthe following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter which is regarded as the invention is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features, and advantages ofthe invention are apparent from the following detailed description takenin conjunction with the accompanying drawings in which:

FIGS. 1A-1B are perspective views of a first embodiment of a torquetransmitting shaft;

FIG. 1C is a cross-section view through C-C of FIG. 1A;

FIG. 1D is a cross-section view through D-D of FIG. 1A;

FIG. 1E is a cross-sectional view of FIG. 1B;

FIG. 2 is a partial section view of a second embodiment of a torquetransmitting shaft;

FIGS. 2A,B is a cross-section view through A-A and B-B of FIG. 2;

FIG. 3 is a partial section view of a third embodiment of a torquetransmitting shaft;

FIGS. 3A and 3B are cross-section views through A-A and B-B,respectively, of FIG. 3;

FIGS. 4A-4C are perspective views of a fourth embodiment of a torquetransmitting shaft;

FIG. 5 is a partial section view of a fifth embodiment of a torquetransmitting shaft;

FIG. 6 is a partial section view of a sixth embodiment of a torquetransmitting shaft;

FIG. 6A is a cross-section view through A-A of FIG. 6;

FIGS. 7A and 7B are perspective views of a seventh embodiment of atorque transmitting shaft;

FIGS. 7C and 7D are cross-section views through C-C and D-D,respectively, of FIG. 7B;

FIGS. 8A and 8B are perspective views of an eighth embodiment of atorque transmitting shaft;

FIG. 8C is a cross-section view through C-C of FIG. 8B; and

FIGS. 9A-9C are views of a ninth embodiment of a torque transmittingshaft.

DETAILED DESCRIPTION

Referring now to the Figures, where the invention will be described withreference to specific embodiments, without limiting same, it is to beunderstood that the disclosed embodiments are merely exemplary of theinvention that may be embodied in various and alternative forms. Thefigures are not necessarily to scale; some features may be exaggeratedor minimized to show details of particular components. Therefore,specific structural and functional details disclosed herein are not tobe interpreted as limiting, but merely as a representative basis forteaching one skilled in the art to variously employ the presentinvention.

Torque transmitting shafts are used to transmit torque or power from atransmission or transaxle to a vehicle wheel. FIGS. 1A-1C illustrates afirst embodiment of a torque transmitting shaft 10. The torquetransmitting shaft 10 includes a first member 20 and a second member 22.The first member 20 extends along an axis 24. The first member 20includes a body 30 extending between a first end 32 and a second end 34disposed opposite the first end 32. The body 30 is a generallycylindrical body having an exterior surface 40 and an inner surface 42.

The inner surface 42 defines an inner bore of the first member 20. Theinner surface 42 defines a plurality of first engagement elements 50.The plurality of first engagement elements 50 are disposed proximate thefirst end 32. In the second embodiment of the torque transmitting shaftillustrated in FIG. 2, the inner surface 42 defines a plurality ofsecond engagement elements 52. The plurality of second engagementelements 52 are disposed proximate the second end 34.

The second member 22 extends along the axis 24. The second member 22 isreceived within the first member 20. The second member 22 has a firstend portion 60, a second end portion 62 disposed opposite the first endportion 60, and an intermediate portion 64. The intermediate portion 64extends between the first end portion 60 and the second end portion 62.

The first end portion 60 has a first end portion diameter. The secondend portion 62 has a second end portion diameter. The intermediateportion 64 has an intermediate portion diameter. The intermediateportion diameter is less than the first end portion diameter and thesecond end portion diameter such that the second member 22 has a dogbone shape when viewed from the side.

In some embodiments, the first end portion 60, the second end portion62, and the intermediate portion 64 are of a one-piece construction madeof the same material. In other embodiments, the first end portion 60,the second end portion 62, and the intermediate portion 64 are providedas separate components that are joined together by a variety of methods.The intermediate portion 64 is made of a first material and the firstend portion 60 and the second end portion 62 are made of a secondmaterial different from the first material, as shown in FIG. 1E. Forexample, the first end portion 60 and the second portion 62 may be madeof steel while the intermediate portion 64 is made of aluminum.

The intermediate portion 64 has a first transition region 70 and asecond transition region 72. The first transition region 70 extends froma first end of the intermediate portion 64 towards the first end portion60. The first transition region 70 provides a gradual transition fromthe smaller intermediate portion diameter to the larger first endportion diameter. The diameter of the first transition region 70increases from the first end of the intermediate portion 64 towards thefirst end portion 60.

The second transition region 72 extends from a second end of theintermediate portion 64 towards the second end portion 62. The secondtransition region 72 provides a gradual transition from the smallerintermediate portion diameter to the larger second end portion diameter.The diameter of the second transition region 72 increases from thesecond end of the intermediate portion 64 towards the second end portion62. The second transition region 72 abuts a flanged surface 76 of thesecond end portion 62.

The first end portion 60 is configured to be rotatable relative to thefirst member 20. The first end portion 60 is rotatable relative to thefirst end 32 of the first member 20 while a torque is applied to thesecond member 22.

The first end portion 60 has a first spline portion 80. The first splineportion 80 is disposed between the first transition region 70 and an endof the first end portion 60. The first spline portion 80 is configuredas a plurality of torque transmitting grooves, torque transmittingserrations, gear teeth, or the like. Each member of the first splineportion 80 is received within or between corresponding first engagementelements of the plurality of first engagement elements 50.

In at least one embodiment, a first sealing member 82 is provided. Thefirst sealing member 82 is disposed proximate the first end 32 of thefirst member 20. The first sealing member 82 engages the first end 32 ofthe first member 20 and a portion of the first end portion 60 of thesecond member 22. The first sealing member 82 is configured to inhibitforeign objects or particles from entering the inner bore of the firstmember 20. The first sealing member 82 inhibits or prevents contaminantsfrom intruding the plurality of first engagement elements 50 and thefirst spline portion 80. The first sealing member 82 is configured as afriction washer.

The second end portion 62 is fixedly positioned relative to the firstmember 20. The second end portion 62 is fixedly positioned relative tothe second end 34 of the first member 20 while an input torque isapplied to the second member 22. The second end 34 of the first member20 abuts and is fixed to the flanged surface 76 of the second endportion 62. The second end 34 is joined to the second end portion 62.The second end 34 is joined to the second end portion 62 by a variety ofmethods such as welding, press fit, swaging, fasteners, brazing, a pinextending from at least one of an end surface of the second end 34 orthe flanged surface 76 of the second end portion 62 that is receivedwithin an opening defined by at least one of the end surface of thesecond end 34 or the flanged surface 76 of the second end portion 62.

In the second embodiment of the torque transmitting shaft illustrated inFIG. 2, the second end portion 62 is configured to be rotatable relativeto the first member 20. The second end portion 62 is rotatable relativeto the second end 34 of the first member 20 while an input torque isapplied to the second member 22.

The second end portion 62 has a second spline portion 84. The secondspline portion 84 is disposed between the second transition region 72and an end of the second end portion 62. The second spline portion 84 isconfigured as a plurality of torque transmitting grooves, torquetransmitting serrations, gear teeth, or the like. Each member of thesecond spline portion 84 is received within or between correspondingfirst engagement elements of the plurality of first engagement elements50.

A second sealing member 86 is provided. The second sealing member 86 isdisposed proximate the second end 34 of the first member 20. The secondsealing member 86 engages the second end 34 of the first member 20 and aportion of the second end portion 62 of the second member 22. The secondsealing member 86 is configured to inhibit foreign objects or particlesfrom entering the inner bore of the first member 20. The second sealingmember 86 inhibits or prevents contaminants from intruding the pluralityof second engagement elements 52 and the second spline portion 84. Thesecond sealing member 86 is configured as a friction washer.

The torque transmitting shaft 10 is configured to provide multipletorsional stiffness rates while a torque is applied to the second member22. The multiple torsional stiffness rates are based on geometry andmaterial characteristics of the second member 22 and a tangentialclearance that exists between the plurality of first engagement elements50 and the first spline portion 80 and/or the plurality of secondengagement elements 52 and the second spline portion 84.

A first torsional stiffness rate is provided by at least one of thefirst member 20 and the second member 22. The first torsional stiffnessrate is provided while a first torque is applied to the second member 22and while there is a tangential clearance between a member of the firstspline portion 80 and an engagement element of the plurality of firstengagement elements 50, as shown in FIG. 1C.

A second torsional stiffness rate is provided by at least one of thefirst member 20 and the second member 22. The second torsional stiffnessrate is provided while a second torque, greater than the first torque,is applied to the second member 22 and while there is no tangentialclearance between the member of the first spline portion 80 and theengagement element of the plurality of first engagement elements 50, asshown in FIG. 1D. The second torsional stiffness rate is greater thanthe first torsional stiffness rate.

Multiple other torsional stiffness rates may be provided by at least oneof the first member 20 and the second member 22. A subsequent torsionalstiffness rate is provided while a torque is applied to the secondmember 22 and while there is a tangential clearance between a member ofthe second spline portion 84 and an engagement element of the pluralityof second engagement elements 52. Another torsional stiffness rate isprovided while a torque is applied to the second member 22 and whilethere is no tangential clearance between a member of the second splineportion 84 and the engagement element of the plurality of secondengagement elements 52. The another torsional stiffness rate is greaterthan the subsequent torsional stiffness rate.

In some embodiments, a lubricant 88 is applied to at least one of theplurality of first engagement elements 50 and the first spline portion80. The lubricant 88 is applied to at least one of the plurality ofsecond engagement elements 52 and the second spline portion 84. Theapplication of the lubricant 88 inhibits or reduces squeaking or noise,vibration, or harshness due to the engagement between the plurality offirst engagement elements 50 and the first spline portion 80 and/or theplurality of second engagement elements 52 and the second spline portion84.

FIG. 3 illustrates a third embodiment of the torque transmitting shaft.The torque transmitting shaft includes an intermediate part 90. Theintermediate part 90 includes an outer surface 92 and an interiorsurface 94. The outer surface 92 engages the inner surface 42 of thefirst member 20. The interior surface 94 defines a plurality ofintermediate engagement elements 96. The intermediate engagementelements 96 are configured to receive a member of an intermediate splineportion 100 of the intermediate portion 64. The intermediate splineportion 100 is disposed between the first spline portion 80 and thesecond spline portion 84. The intermediate spline portion 100 isconfigured as a plurality of torque transmitting grooves, torquetransmitting serrations, gear teeth, or the like.

The intermediate part 90 is rotatable relative to the second member 22.Each member of the intermediate spline portion 100 is received withincorresponding engagement elements of the plurality of intermediateengagement elements 96.

Intermediate part 90 is made of a material different than the firstmember 20 and the second member 22. The intermediate part 90 is made ofmaterial that is more compliant than the first member 20 and the secondmember 22. The intermediate part 90 is configured to provide dampingduring engagement of a member of the intermediate spline portion 100 andan element of the plurality of intermediate engagement elements 96.

A third torsional stiffness rate is provided by at least one of thefirst member 20, the second member 22, and the intermediate part 90. Thethird torsional stiffness rate is provided while a third torque isapplied to the second member 22 and while there is a tangentialclearance between a member of the intermediate spline portion 100 andthe plurality of first engagement elements 50 and while there is notangential clearance between a member of the intermediate spline portion100 and an engagement element of the plurality of intermediateengagement elements 96.

A fourth torsional stiffness rate is provided by at least one of thefirst member 20, the second member 22, and the intermediate part 90. Thefourth torsional stiffness rate is provided while a fourth torque isapplied to the second member 22 and while there is a tangentialclearance between the member of the intermediate spline portion 100 andthe engagement element of the plurality of intermediate engagementelements 96. The third torsional stiffness rate is greater than thefourth torsional stiffness rate.

FIGS. 4A-4C illustrates a fourth embodiment of the torque transmittingshaft. The fourth embodiment includes an engagement part 110. Theengagement part 110 is a compressible member configured as a spring oran elastomeric damper. The engagement part 110 is disposed between thefirst sealing member 82 and a portion of the first spline portion 80. Inat least one embodiment, the engagement part 110 is disposed between thesecond sealing member 86 and a portion of the second spline portion 84.

The engagement part 110 is disposed between adjacent elements of theplurality of first engagement elements 50. The engagement part 110 isdisposed between a member of the first spline portion 80 and an elementof the plurality of first engagement elements 50. The engagement part110 is molded or injected between the first spline portion 80 and theplurality of first engagement elements 50. In response to rotation ofthe first end portion 60 of the second member 22 relative to the firstend 32 of the first member 20 at least one of an element of theplurality of the first engagement elements 50 and a member of the firstspline portion 80 at least partially compresses the engagement part 110to vary the torsional stiffness rate of the torque transmitting shaft10.

A fifth torsional stiffness rate is provided by at least one of thefirst member 20, the second member 22, and the engagement part 110. Thefifth torsional stiffness rate is provided while a fifth torque isapplied to the second member 22 and while a member of the first splineportion 80 at least partially compresses the engagement part 110 betweena member of the first spline portion 80 and an element of the pluralityof first engagement elements 50.

A sixth torsional stiffness rate is provided by at least one of thefirst member 20, the second member 22 and the engagement part 110. Thesixth torsional stiffness rate is provided while a sixth torque, greaterthan the fifth torque, is applied to the second member 22 and while theengagement part 110 is either completely compressed or the member of thefirst spline portion 80 engages the element of the plurality of firstengagement elements 50. The sixth torsional stiffness rate is greaterthan the fifth torsional stiffness rate. The sixth torsional stiffnessrate may be approximately equal to the second torsional stiffness rate.

FIG. 5 illustrates a fifth embodiment of the torque transmitting shaft.The torque transmitting shaft 120 includes a first member 122 and asecond member 124. The first member 122 has a generally cylindrical body130 extending along an axis 126 between a first end 132 and a second end134. The generally cylindrical body 130 has an inner surface 136.

The inner surface 136 defines an inner bore of the first member 122. Theinner bore extends from the first end 132 towards the second end 134.The first end 132 defines an opening and the second end 134 is closedand does not define an opening. The second end 134 defines a closed endsurface. The inner surface 136 defines a plurality of engagementelements 138 disposed proximate the first end 132.

The second member 124 extends along the axis 126. The second member 124is received within the first member 122. The second member 124 has afirst end portion 140 and an intermediate portion 142. The first endportion 140 is configured to be rotatable relative to the first member122. The first end portion 140 is rotatable relative to the first end132 of the first member 122 while an input torque is applied to thesecond member 124.

The first end portion 140 has a spline portion 150. The spline portion150 is configured as a plurality of torque transmitting grooves, torquetransmitting serrations, gear teeth, or the like. Each member of thespline portion 150 is received within or between corresponding firstengagement elements of the plurality of engagement elements 138.

The intermediate portion 142 extends from the first end portion 140along the axis 126. The intermediate portion 142 includes an end 154disposed opposite the first end portion 140. The end 154 of theintermediate portion 142 is fixedly attached to the second end 134 ofthe first member 122. The end 154 is fixedly attached to the closed endsurface of the second end 134 by press fitting, swaging, solid-statejoining, or the like.

The torque transmitting shaft 120 is configured to provide multipletorsional stiffness rates while a torque is applied to the second member124. A first torsional stiffness rate is provided by the first member122. The first torsional stiffness rate is provided by the first member122 while a first torque is applied to the first member 122 and whilethere is a tangential clearance between a member of the spline portion150 and an engagement element of the plurality of engagement elements138.

A second torsional stiffness rate is provided by at least one of thefirst member 122 and the second member 124. The second torsionalstiffness rate is provided by at least one of the first member 122 andthe second member 124 while a second torque is applied to the firstmember 122 and while there is no tangential clearance between the memberof the spline portion 150 and the engagement element of the plurality ofengagement elements 138. The second torsional stiffness rate is greaterthan the first torsional stiffness rate.

The fifth embodiment of the torque transmitting shaft illustrated inFIG. 5, the first end portion 140 and the intermediate portion 142 areof a one-piece construction. The sixth embodiment of the torquetransmitting shaft illustrated in FIG. 6, the first end portion 140 andthe intermediate portion 142 are provided as separate components thatare joined together by a variety of solid-state joining methods.

A seventh embodiment of a torque transmitting shaft is illustrated inFIGS. 7A and 7B. The torque transmitting shaft 160 includes a firstmember 170, a second member 172, a first pin 174, and a bushing 176.

The first member 170 includes a generally cylindrical body 180 extendingalong an axis 182 between a first end 184 and a second end 186. Thegenerally cylindrical body 180 has an exterior surface 190 and an innersurface 192. The inner surface 192 defines an inner bore of the firstmember 170.

The generally cylindrical body 180 defines a first opening 200 and asecond opening 202 spaced apart from the first opening 200. The firstopening 200 is disposed proximate the first end 184. The first opening200 extends from the exterior surface 190 to the inner surface 192 alongan opening axis disposed substantially perpendicular to the axis 182.The first opening 200 extends completely through the generallycylindrical body 180. In the eighth embodiment of the torquetransmitting shaft illustrated in FIGS. 8A and 8B the first opening 200is larger than the second opening 202. The first opening 200 is aslotted opening having a width that extends transverse to the axis 182greater than a diameter of the second opening 202.

The second opening 202 is disposed proximate the second end 186. Thesecond opening 202 extends from the exterior surface 190 to the innersurface 192 along another opening axis disposed substantiallyperpendicular to the axis 182. The second opening 202 extends completelythrough the generally cylindrical body 180.

The second member 172 extends along the axis 182. The second member 172is received within the first member 170. The second member 172 has afirst end portion 210, a second end portion 212, and an intermediateportion 214. The intermediate portion 214 extends between the first endportion 210 and the second end portion 212.

The first end portion 210 has a first end portion diameter. The secondend portion 212 has a second end portion diameter. The intermediateportion 214 has an intermediate portion diameter. The intermediateportion diameter is less than the first end portion diameter and is lessthan the second end portion diameter such that the second member 172 hasa dog bone shape when viewed from the side.

The first end portion 210 defines a first end portion opening 220. Thefirst end portion opening 220 extends completely through the first endportion 210 along an axis disposed substantially perpendicular to theaxis 182. The first end portion opening 220 is proximately aligned withthe first opening 200.

The second end portion 212 defines a second end portion opening 222. Thesecond end portion opening 222 extends completely through the second endportion 212 along an axis disposed substantially perpendicular to theaxis 182. The second end portion opening 222 is proximately aligned withthe second opening 202.

The first opening 200 and the first end portion opening 220 are sized toreceive at least one of the first pin 174 and the bushing 176. A firsttorsional stiffness rate is provided by at least one of the first member170 and the second member 172. The first torsional stiffness rate isprovided while a first torque is applied to the second member 172 andwhile there is a tangential clearance between an exterior surface of thefirst pin 174 and an edge of the first opening 200.

A second torsional stiffness rate is provided by at least one of thefirst member 170, the second member 172, and the bushing 176. The secondtorsional stiffness rate is provided while a second torque, greater thanthe first torque, is applied to the second member and while there is notangential clearance between the exterior surface of the first pin 174and the edge of the first opening 200.

A third torsional stiffness rate is provided by at least one of thefirst member 170, the second member 172, and the bushing 176. The thirdtorsional stiffness rate is provided while a third torque is applied tothe second member 172 and while the first pin 174 at least partiallycompresses the bushing 176.

The second opening 202 and the second end portion opening 222 are sizedto receive at least one of a second pin 226 and the bushing 176. Afourth torsional stiffness rate is provided by at least one of the firstmember 170 and the second member 172. The fourth torsional stiffnessrate is provided while a fourth torque is applied to the second member172 and while there is a tangential clearance between an exteriorsurface of the second pin 226 and an edge of the second opening 202.

A fifth torsional stiffness rate is provided by at least one of thefirst member 170, the second member 172, and the bushing 176. The fifthtorsional stiffness rate is provided while a fifth torque, greater thanthe fourth torque, is applied to the second member and while there is notangential clearance between the exterior surface of the second pin 226and the edge of the second opening 202.

A sixth torsional stiffness rate is provided by at least one of thefirst member 170, the second member 172, and the bushing 176. The sixthtorsional stiffness rate is provided while a sixth torque is applied tothe second member 172 and while the second pin 226 at least partiallycompresses the bushing 176.

In the seventh embodiment illustrated in FIGS. 7A and 7B, the firstopening 200 and the first end portion opening 220 receive the first pin174 and the bushing 176 and the second opening 202 and the second endportion opening 222 receive the second pin 226 and the bushing 176, thefirst end portion 210 and the second end portion of 212 are rotatablerelative to each other. The first end portion 210 is rotatable relativeto the first end 184 of the first member 170. The second end portion 212is rotatable relative to the second end 186 of the first member 170.

In the eighth embodiment illustrated in FIGS. 8A and 8B, the firstopening 200 and the first end portion opening 220 receive the first pin174 and the bushing 176 and the second opening 202 and the second endportion opening 222 receive the second pin 226, the first end portion210 is configured to be rotatable and the second end portion 212 isfixedly positioned. The first end portion 210 is rotatable relative tothe first end 184 of the first member 170. The second end portion 212 isfixedly positioned relative to the second end 186 of the first member170.

FIGS. 9A-9C illustrates a ninth embodiment of a torque transmittingshaft 230. The torque transmitting shaft 230 includes a first member240, a second member 242, and a plurality of engaging rolling elements244. The first member 240 extends along an axis 246. The first member240 includes a body 250 extending between a first end 252 and a secondend 254 disposed opposite the first end 252. The body 250 is a generallycylindrical body having an exterior surface 260 and an inner surface262.

The inner surface 262 defines an inner bore of the first member 240. Theinner surface 262 defines a plurality of first engagement elements 270.The plurality of first engagement elements 270 are disposed proximatethe first end 252.

The second member 242 extends along the axis 246. The second member 242is received within the first member 240. The second member 242 has afirst end portion 280, a second end portion 282 disposed opposite thefirst end portion 280, and an intermediate portion 284. The intermediateportion 284 extends between the first end portion 280 and the second endportion 282.

The first end portion 280 has a first end portion diameter. The secondend portion 282 has a second end portion diameter. The intermediateportion 284 has an intermediate portion diameter. The intermediateportion diameter is less than the first end portion diameter and thesecond end portion diameter such that the second member 242 has a dogbone shape when viewed from the side.

The first end portion 280 is configured to be rotatable relative to thefirst member 240. The first end portion 280 is rotatable relative to thefirst end 252 of the first member 240 while a torque is applied to thesecond member 242.

The first end portion 280 has a first spline portion 290. The firstspline portion 290 is disposed proximate the first end 252 of the firstmember 240. The first spline portion 290 is configured as a plurality oftorque transmitting grooves, torque transmitting serrations, gear teeth,or the like. Each member of the first spline portion 290 is receivedwithin or between corresponding first engagement elements of theplurality of first engagement elements 270.

In at least one embodiment, a first sealing member 292 is provided. Thefirst sealing member 292 is disposed proximate the first end 252 of thefirst member 240. The first sealing member 292 engages the first end 252of the first member 240 and a portion of the first end portion 280 ofthe second member 242. The first sealing member 292 is configured toinhibit foreign objects or particles from entering the inner bore of thefirst member 240. The first sealing member 292 inhibits or preventscontaminants from intruding the plurality of first engagement elements270 and the first spline portion 290. The first sealing member 292 isconfigured as a friction washer.

The second end portion 282 is fixedly positioned relative to the firstmember 240. The second end portion 282 is fixedly positioned relative tothe second end 254 of the first member 240 while an input torque isapplied to the second member 242. The second end 254 of the first member240 is fixed to the second end portion 282. The second end 254 is joinedto the second end portion 282. The second end 254 is joined to thesecond end portion 282 by a variety of methods such as welding, pressfit, swaging, fasteners, brazing, a pin and groove, or the like.

The plurality of engaging rolling elements 244 are disposed between thefirst member 240 and the second member 242. The plurality of engagingrolling elements 244 are ball members, rolling pins, or the likedisposed within a cage. The plurality of engaging rolling elements 244are disposed between the plurality of first engagement elements 270 ofthe first member 240 and the first spline portion 290 of the secondmember 242.

A first torsional stiffness rate is provided by the second member 242.The first torsional stiffness rate is provided while a first torque isapplied to the second member 242 and while there is a tangentialclearance between a member of the first spline portion 290, anengagement element of the plurality of first engagement elements 270,and an element of the plurality of engaging rolling elements 244, asshown in FIG. 9B.

A second torsional stiffness rate is provided by at least one of thefirst member 240 and the second member 242. The second torsionalstiffness rate is provided while a second torque, greater than the firsttorque, is applied to the second member 242 and while there is notangential clearance between the member of the first spline portion 290,the engagement element of the plurality of first engagement elements270, and the element of the plurality of engaging rolling elements 244,as shown in FIG. 9C. The second torsional stiffness rate is greater thanthe first torsional stiffness rate.

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description.

Having thus described the invention, it is claimed:
 1. A torquetransmitting shaft comprising: a first member extending along an axis,the first member having an inner surface extending between a first endand a second end, the inner surface defining a plurality of firstengagement elements disposed proximate the first end; and a secondmember extending along the axis and received within the first member,the second member having a first end portion, a second end portionhaving a flanged surface that abuts the second end, and an intermediateportion extending between the first end portion and the second endportion, the first end portion having a first spline portion, eachmember of the first spline portion is received within correspondingengagement elements of the plurality of first engagement elements; and afirst torsional stiffness rate is provided by the second member while afirst torque is applied to the second member and while there is atangential clearance between the first spline portion and the pluralityof first engagement elements and a second torsional stiffness rate isprovided by at least one of the first member and the second member whilea second torque is applied to the second member and while there is notangential clearance between the member of the first spline portion andan engagement element of the plurality of first engagement elements. 2.The torque transmitting shaft of claim 1, wherein the first end portionis rotatable relative to the first member.
 3. The torque transmittingshaft of claim 1, wherein the second end portion is fixedly positionedrelative to the first member.
 4. The torque transmitting shaft of claim1, wherein the second torsional stiffness rate is greater than the firsttorsional stiffness rate.
 5. The torque transmitting shaft of claim 1,wherein the intermediate portion has an intermediate portion diameterless than a first end portion diameter and a second end portiondiameter.
 6. The torque transmitting shaft of claim 1, wherein theintermediate portion is made of a first material and the first endportion and the second end portion are made of a second materialdifferent from the first material.
 7. The torque transmitting shaft ofclaim 1, wherein a lubricant is applied to at least one of the pluralityof first engagement elements and the first spline portion.